The most common infectious complication following organ transplantation is cytomegalovirus (CMV), resulting in increased allograft rejection and mortality. Current virology research suggests that the presence of antigen- specific ?polyfunctional? T cells is essential for viral control; when encountering target, these rare cells are capable of producing multiple inflammatory cytokines (e.g., IFNg, TNFa, IL-2) and effecting rapid cytolysis, while those cells expressing only one (i.e., monofunctional) or no cytokines have been associated with progressively less protection. Unfortunately, assays for quantification of polyfunctional T cells remains arduous and lack inter-facility reproducibility; additionally, the mechanisms driving the generation and maintenance of such cells remains unknown. My preliminary data in kidney transplant recipients reveals that those lacking polyfunctional CMV responses are at increased risk of CMV reactivation. Importantly, I have also found that T cell exhaustion is not primarily responsible for discrepancies in CMV-associated functionality observed between patients with and without CMV reactivation, thereby suggesting alternative mechanisms. Therefore, based on preliminary data, the central hypothesis tested is that STAT5- and myc-dependent molecular reprogramming is necessary for the generation and maintenance of CMV-specific polyfunctional T cells, and that expansion of cells with an IL-7-based protocol recapitulates this reprogramming and will produce functional, long-lived cell-based therapies in the event of CMV reactivation. The proposed research will: (1) determine if a transcriptional profile may be used not only to quantify polyfunctional T cells but also identify SOT recipients at risk for CMV reactivation; (2) determine the critical role of STAT5 and myc activation and alterative metabolic pathways expression on the function of CMV-specific polyfunctional T cells; and (3) optimize cytokine-based protocols for the ex-vivo expansion of CMV-specific T cells by characterization of functional, proliferative, and metabolic parameters. My primary career goal is to obtain a tenure-track position and establish an independent research laboratory at a major biomedical institution. My long-term career goal is to establish a career as an independently-funded physician-scientist, with a particular focus in transplant immunology and associated changes in T cells metabolism. To achieve these goals, I will develop my intellectual base, strengthen my leadership skills, and enhance the necessary technical skills through the duration of the proposed study. Valuable training is readily available in the labs of Drs. Murdoch, Chao, and Piantadosi. Furthermore, to promote and bolster my progress during the award period, I have organized a scientific advisory committee of well-established scientists and clinicians with expertise in all areas of the application. Collectively, the proposed research will enhance our understanding of the specific molecular mechanisms regulating the generation and maintenance of polyfunctional T cells in transplant recipients, and may result in better treatment options for transplant recipients with CMV reactivation. ! ! !